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A project log for MultiBot CNC v2

A low cost 3D printed CNC that can be built with minimal tools yet is capable of great things.

David TuckerDavid Tucker 11/12/2021 at 02:560 Comments

I'm getting close to having my new controller up and running.  I have a case printed up that seems to work (so far), I have GRBL-Mega-5x up and running, and I have (almost) finished the wiring.  I just glued the heatsinks on my drivers and am waiting for them to dry.  And I need to make a quick disconnect cable for the rotary axis so I can unplug it without opening the controller case.

The new setup has a few small changes from the old one.  I added in support for a probe to make it easier to mill pcb's and for more consistent tool changes.  I added in the stop, pause, resume buttons. I don't know if these have much value, but I was curious about them. And I removed the negative side limit switches from the machine.  It can now home and use soft limits but no longer supports hard limits.  The hard limits were never stable and since the controller only supports 6 switches this allowed me to use the 4 I still have without a daughterboard.

I received my MKS TFT24 LCD display and added the CNC firmware to it. This was another experiment, but It is not looking very good.  The layout is poor and not very convenient, the display updates slowly, it has no feedback (status), and there does not seem to be a simple way to edit the underlying code.  It is a shame that they did not make this Arduino compatible.  This is really nothing more than an arduino with an LCD display and a flash drive. It should be trivial to make our own firmware for it.  However from what I can tell no one has successfully done this.  Anyway I will know more once the machine is up and running, but it is not looking promising.

Finally for a future project I have ordered two 800 mm long 16 mm steel rods and a pair of LM16LUU bearings.  I want to run some tests to see how much stiffer these rods are than 12 mm rods.  And I have an idea that I can replace 3 of the 12 mm rods on the X axis using only one 16 mm rod at the bottom and one 12 mm rod at the top.  My theory is that this would be stiffer than my current setup while being cheaper than buying 4 12mm rods and bearings.

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